Electronic devices include various pathways on which data must be transferred at high speed. One example of a high-speed data pathway is a data bus between a processor and a memory device. When signaling rates are high, it is generally necessary to use impedance matching signal terminations on pathways to control artifacts such as electrical reflections, inter-symbol interference, overshoot, undershoot, and ringing. Terminations consume significant electrical power, however, and are therefore not used when signal rates are low enough to avoid the foregoing artifacts.
Devices that use high signal rates and thus require signal termination have heretofore often been AC line powered or contained a sufficiently large battery pack (a laptop, for example) so that the power drain of signal termination circuitry could be ignored. In addition, many electronic components, memory devices such as dynamic random access memory (DRAM) device, for example, contain built-in features like on-die termination (ODT) which selectively terminate signals based on the direction that a signal is travelling. That is, control circuitry on the DRAM device itself selectively enables signal termination during signal reception and disables it at other times.
Manufacturers continue to look for ways to decrease power use, both to prolong battery life and to reduce the amount of heat that must be dissipated. It would therefore be desirable to provide a system and method for dynamically controlling signal termination that reduces energy use.